* @return an array of rescorer builders, filtered to exclude null values
     */
    public RescorerBuilder<?>[] getRescorers(final Map<String, Object> params) {
        return queryRescorerList.stream().map(r -> r.evaluate(params)).filter(b -> b != null).toArray(n -> new RescorerBuilder<?>[n]);
    }

    /**
     * Adds a query rescorer for post-processing search results.